how much RAM will Leo "read"?

I understand that 4 GB will be fully "readable" but what about more, like 6GB or 8GB?

It's not Leopard that's limited, it's the chipset itself. So if the motherboard supports more than 4GB of memory, then Leopard will access it just fine.

Leopard is a 64-bit OS, so it can handle somewhere in the terabytes of RAM

I see

And the max todays chipsets can handle is? 4GB or more?

But what about them Mac Pro's having like 16GB of RAM onboard?

Bilobrkster said:

I see

And the max todays chipsets can handle is? 4GB or more?

Click to expand...

From what I've gathered the current MacPro supports upto 16GB, but it all depends on number of DIMM slots on the motherboard.
Some Intel Server Boards support upto 32GB

Consumer motherboards are pretty much all limited to 4Gb.

It's professional products like the Pro and servers which support more.